1,3,3-trimethyl-bis(alpha,t-butylperoxyisopropyl)-1-phenylindane

ABSTRACT

1,3,3-TRIMETHYL-BIS(A-T-BUTYLPEROXYISOPROPYL)-1-PHENYLINDANES IN WHICH THE A-T-BUTYLPEROXYISOPROPYL GROUPS ARE ATTACHED IN THE 6- AND 4&#39;&#39;-, AND 6- AND 3&#39;&#39;, 5- AND 4&#39;&#39;, 5&#39;&#39;- AND 3&#39;&#39;-, 7- AND 4&#39;&#39;, OR 7- AND 3&#39;&#39; POSITIONS ARE HEATED IN CONTACT WITH CURABLE POLYMERS WHEREBY CROSSLINKING OF THE POLYMER IS EFFECTED.

United States Patent 3,773,724 1,3,3-TRIMETHYL-BIS(a,t-BUTYLPEROXYISO-PROPYL)-1-PHENYLINDANE Frederick G. Schappell, Newark, Del., assignor toHercules Incorporated, Wilmington, Del.

No Drawing. Application Dec. 31, 1969, Ser. No. 889,685,

now Patent No. 3,668,259, which is a continuation-inpart of abandonedapplication Ser. No. 741,850, July .2, 1968. Divided and thisapplication Sept. 29, 1971, Ser. No. 184,955

Int. Cl. C08c 17/28; C08d 13/28; C08f 27/00 US. Cl. 260-465 G 8 ClaimsABSTRACT OF THE DISCLOSURE 1, 3 ,3 -trimethyl-bis(u-t-Uutylperoxyisopropyl) -1-phenylindanes in which theu-t-butylperoxyisopropyl groups are attached in the 6- and 4'-, 6- and3'-, and 4'-, 5'- and 3'-, 7- and 4'-, or 7- and 3-positions are heatedin contact with curable polymers whereby crosslinking of the polymer isefiected.

This application is a division of my copending US. application. Ser. No.889,685, filed Dec. 31, 1969, now US. 3,668,259, which is in turn acontinuation-in-part of application Ser. No. 741,850, filed July 2,1968, now abandoned.

This invention relates to organic peroxides and, more particularly, toorganic peroxides which are non-blooming, odor-free curing agents forolefin polymers, and to compositions capable of being crosslinkedtherewith.

In Pat. 3,402,205 there is described a class of peroxides in which anaryl nucleus is substituted by two to four t-alkylperoxyisopropylgroups. The aryl nucleus was exemplified by groups containing either onebenzene ring or more than one benzene ring joined together directly byfusion or by a single atom.

It has now been found that a bisperoxide of the formula group isattached to a benzene ring is an organic peroxide having excellentcuring properties for polyethylene and greater scorch resistance thanrelated bisperoxides and is non-blooming.

The peroxides of this formula have the nucleus of an tat-methylstyrenedimer, i.e.,

3,773,724 Patented Nov. 20, 1973 and they can bemade by isopropylatinga-methylstyrene dimer to a diisopropyl-a-methylstyrene dimer, oxidizingthe latter to a bis(u-hydroxyisopropyl)-a-methylstyrene dimer, andreacting this last-named compound with tbutylhydroperoxide. Thebisperoxides of this invention can also be made from isomers such asp-isopropyl-amethylstyrene dimer, or from m-isopropyl-a-methylstyrenedimer.

This group of bisperoxides is exemplified by 1,3,3-trimethyl-6,4'-bis(tbutylperoxyisopropyl)-l-phenylindane which is prepared by oxidizing thedimer of p-isopropylor-methylstyrene, i.e.,1,3,3-trimethyl-6,4-bis(isopropyl)- l-phenylindane to the dialcohol,1,3,3-trimethyl-6,4'-bis (hydroxyisopropyl)-1-phenylindane, and thenreacting the dialcohol with t-butylhydroperoxide to form the 1,3,3-trimethyl-6,4'-bis(t-butylperoxyisopropyl) 1 phenylindane.

The process of preparation and a description of the properties of thisnovel bisperoxide are illustrated in the following examples, in whichall parts and percentages are by weight.

EXAMPLE 1 1,3,3-trimethyl-6,4'-bis(isopropyl) 1, phenylindane wasprepared by heating 100 parts p-isopropyl-u-methyk styrene with 180parts aqueous sulfuric acid at 80- C., with stirring for one hour andrecovered by separating the acid layer, washing the organic phase withdilute aqueous sodium hydroxide and water, and distilling to obtain 56parts of product which melted at 5354 C,

1,3,3-trimethyl-6,4-bis(hydroxyisopropyl) 1 phenylindane was prepared bydispersing moist oxygen gas into parts of1,3,3-trimethyl-6,4'-bis(isopropyl)-1-phenylindane while rapidlystirring with 25 parts of 50% aqueous sodium hydroxide at -115 C. forabout 10 hours and was purified by dissolving in benzene and washingfree of salts of acidic materials with 4% aqueous sodium hydroxide, andsubsequent countercurrent extraction of an acetonitrile solution thereofwith hexane followed by distilling otf the acetonitrile.

1,3,3 trimethyl 6,4 bis(t-butylperoxyisopropyl)-1- phenylindane wasprepared by heating at 47-60 C. a. solution of 32 parts1,3,3-trimethyl-6,4-bis(hydroxyisopr0pyl)-1-phenylindane, 37.2 parts 82%t-butylhydroperoxide and 0.38 part p-toluenesulfonic acid in 100 partsheptane under reflux under reduced pressure with water removal for about3 hours and, subsequently, purifying by washing with 8% sodium hydroxideand then with water and distilling off the heptane. The yieldofbisperoxide was 12.4% of theory as shown by infrared and iodometricanalyses.

A sample of the above1,3,3-trimethyl-6,4'-bis(t-butylperoxyisopropyl)-1-phenylindane wascompounded with low density polyethylene at the rate of 1 part peroxideper hundred of polyethylene (1 phr.) and also at the rate of .2 phr. Thepolyethylene compositions containing also 0.5 phr. antioxidant (AgeRiteResin D-R. T. Vanderbilt Co. trademark for polymerized trimethyldihydroquinoline) were then vulcanized by heating one part at 177 C. for10 minutes, and another part at 188 C. for 10 minutes. The results onthe product were shown by gel and swell tests as follows:

m min., 177 0. 10 min'., 188 0.

Crosslinker level Gel Swell Gel Swell 3 A filled sample of polyethylenewas similarly prepared and tested using 40 phr. carbon black in additionto 0.5 phr. antioxidant (AgeRite Resin D) and 1 and 2 phr. bisperoxide.The test results were shown by gel and swell tests as follows:

mln., 177 0. 10 mln., 188 C.

Grossllnker level Gel Swell Gel Swell EXAMPLE 2 A mixture of 7 parts of1,3,3-trimethyl-5,3'-bis(isopropyl)-1-phenylindane and 1 part of1,3,3-trimethyl-7,3-bis- (isopropyl)-1-phenylindane was prepared byheating 100 parts of m-isopropyl-a-rnethylstyrene with 25 parts of 80%aqueous sulfuric acid at about 90 C. with stirring for 1 hour. Theproduct was recovered after dilution with 100 parts of water tofacilitate removal of the acid layer. After washing with aqueous sodiumhydroxide and water, the organic layer was dried and distilled in thepresence of'potassium carbonate to yield 34 parts of a liquid, boilingin the range 148-158 C. at 0.85 torr. Gas chromatographic analysisshowed the product contained 98.7% phenylindane compounds.

A mixture of 1,3,3-trimethyl-5,3-bis(hydroxyisopropyl) and1,3,3-trimethyl-7,3-bis(hydroxyisopropyl)-1-phenylindane was prepared asin Example 1 by the action of oxygen on 25 parts of the hydrocarbonmixture in the presence of 100 parts of 50% aqueous sodium hydroxide.The reaction was performed at 100-115 C. for about 9 hours, after which19.2 parts of diol mixture was purified and isolated as described inExample 1.

A mixture of1,3,3-trimethyl-5,3'-bis(a-tbutylperoxyisopropyl)-1-phenylindane and1,3,3-trimethyl-7,3-bis(at-butylperoxyisopropyl)-1-phenylindane wasprepared by heating 12 parts of the diol mixture with 15 parts 82%t-butylhydroperoxide and 0.38 part p-toluenesulfonic acid in 50 partsheptane under reflux under reduced pressure for 1.75 hours. Purificationof the final product was effected as in Example 1.

EXAMPLE 3 A mixture of six diisopropyl-a-methylstyrene dimers composedof the 6,4-; 6,3'-; 5,4'-; 5,3-; 7,4-; and 7,3- diisopropylated isomerswere prepared by heating 100 parts of a 2:1 mixture of mandp-isopropyl-a-methylstyrene with 100 parts of 80% aqueous sulfuric acidwith stirring at 90 C. for 1 hour. The product was worked up anddistilled as in Example 2 to give 30 parts of an oil, boiling at 160-175C. at 1.0-1.1 torr.

Oxidation of parts of this mixture was performed as in Example 1 in thepresence of 50 parts 50% aqueous sodium hydroxide at 100-115 C. for 11hours. After the termination of the oxidation, the product was worked upand purified as in Example 1 to give 11 parts 1,3,3-trimethyl-bis(hydroxyisopropyl)-l-phenylindane (mixed isomers of diols).

1,3,3 trimethyl bis(a t butylperoxyisopropyl) 1- phenylindane (mixedisomers) was prepared by heating at 45-61 C. a solution of 10 parts ofthe mixed diols, 15 parts 82% t-butylhydroperoxide, 0.38 partp-toluenesulfonic acid and 50 parts heptane under reflux under reducedpressure with water removal for 2 hours. Purifica tion of the finalproduct was effected as in Example 1.

EXAMPLE 4 A formulation of EPM (100 parts) 75 phr. MT Black, 5 phr. zincoxide and 2.35 parts of the bisperoxide of Example 1 was prepared andcompared with a similar formulation using 2.7 phr. dicumylperoxide and,also with a similar formulation using 1.7 phr.m-bis(a-t-butylperoxyisopropyl)benzene. These formulations aredesignated 4A, 4B and 4C, respectively. The compositions 4A, 4B and 4Cwere separately mixed on a two-roll mill and were sheeted into teststrips from which samples were cut for vulcanization testing on theMonsanto Oscillating Disk Rheometer. This rheometer is a device whichmeasures dynamic properties, curing, and processing characteristics ofelastomer compositions during the curing cycle. The sample from the teststrip (4A, 4B and 4C) was placed in the device, and a disk embedded inthe sample was subjected to oscillatory motion by a motor driveneccentric wherein the force (torque) required to oscillate the disccould be measured electronically while heating at controlledtemperatures.

The tests were carried out at 320 F. and 330 F. The first torquemeasurement taken was the minimum reached at initial equilibrium beforecure began, T-min. Subsequent torque measurements were taken atintervals of time so as to be able to plot a curve of torque againsttime. The test was stopped at the time that maximum torque (T-max.) wasreached. The time (1+1) to reach minimum torque (T-min.) plus 1 torqueunit and the time to reach of T-max. was also noted. The results were asfollows:

These results show that the compound of this invention (4A) requires alonger time for T to be reached, and this is indicative that thecompound of this invention has a longer half-life than either of therelated peroxides of 4B or 4C. The lower scorch resistance of thecompound is attributed to the longer half-life. The longer half-life isalso advantageous in controlling extent of curing of the polymercompositions.

In crosslinking of crosslinkable polymers in accordance with thisinvention, the crosslinkable polymer is admixed with the bisperoxide ofthe present invention by any of the usual techniques conventionallyemployed in the elastomer field, as, for instance, by passage throughmixing rolls or by dispersion using conventional mixers. I

The crosslinkable polymers which are particularly used in this processare polyethylene, natural rubber, polystyrene, polyisoprene,cis-4-polybutadiene, poly(chloroprene), silocone rubber, EPM, EPDM, SBR,and NBR. These may be unfilled or filled with the usual black andnon-black fillers useful in compounding of these polymers.

EPM is an elastomeric ethylene-propylene copolymer and EPDM is anelastomeric terpolymer of ethylene, propylene and a diene such, forexample, as 1,4-hexadiene and dicyclopentadiene. The latter M in theabove designation indicates elastomers having a saturated chain of thepolymethylene typesee ASTM Designation: D1418-67. NBR isnitrile-butadiene rubber, SBR is styrene-butadiene rubber.

What I claim and desire to protect by Letters Patent is:

1. A composition capable of being crosslinked by heating comprising apolymeric material of the group consisting of polyethylene, naturalrubber, polystyrene, polyisobutylene, cis-4-polybutadiene,poly(chloroprene), silicone rubber, ethylene-propylene copolymer,terpolymers of ethylene, propylene and a diene, styrene-butadiene rubberand nitrile-butadiene rubber and a crosslinking amount of a bisperoxidehaving the formula group is attached to a benzene ring.

2. A composition capable of being crosslinked by heating comprising apolymeric material of the group consisting of polyethylene, naturalrubber, polystyrene, polyisobutylene, cis-4-polybutadiene,poly(chloroprene), silicone rubber, ethylene-propylene copolymer,terpolymers of ethylene, propylene and a diene, styrene-butadiene rubberand nitrile-butadiene rubber and a crosslinking amount of thebisperoxide of claim 1 wherein a t-butylperoxyisopropyl group isattached to each benzene ring.

3. A composition capable of being crosslinked by heating comprisingpolyethylene and a crosslinking amount of the bisperoxide of claim 1wherein a t-butylperoxyisopropyl group is attached to each benzene ring.

4. A composition capable of being crosslinked by heating comprisingpolyethylene and a crosslinking amount of the bisperoxide of claim 1wherein the t-butylperoxyisopropyl groups are attached at positions 6and 4'.

5. A composition capable of being crosslinked by heating comprisingpolyethylene and a crosslinking amount of the bisperoxide of claim 1wherein the t-butylperoxyisopropyl groups are attached at positions 5and 3.

6. A composition capable of being crosslinked by heating comprisingpolyethylene and a crosslinking amount of the bisperoxide of claim 1wherein the t-butylperoxyisopropyl groups are attached at positions 7and 3'.

7. A compostion capable of being crosslinked by heating comprisingpolyethylene and a crosslinking amount of a isomeric mixture of thebisperoxide of claim 1 wherein the t-butylperoxyisopropyl groups areattached at positions 5 and 3 in one isomer and at 7 and 3' in theother.

8. A composition capable of being crosslinked by heating comprisingpolyethylene and a crosslinking amount of a isomeric mixture of thebisperoxide of claim 1 wherein the t-butylperoxyisopropyl groups areattached at positions 6 and 4', 6 and 3', 5 and 4', 5 and 3', 7 and 4,and 7 and 3'.

References Cited UNITED STATES PATENTS 3,668,259 6/1972 Schappell26094.9 GA 3,658,914 4/1972 Greg0ry 260610 R 3,402,205 9/ 1968 Gregory2606l0 B JOSEPH L. SCHOFER, Primary Examiner A. HOLLER, AssistantExaminer US. Cl. X.R.

260-465 G, 80.7, 80.78, 83.3, 85.1, 88.2 S, 92.3, 93.5 A, 94.7, 94.8,773

UNITED STATES PATENT OFFICE- CERTIFICATE OF CORRECTION Dated November20, 1973 Patent No. 3 773,724.

Inventor(s) rick G. Schappell It is certified that error appears in'theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Printed Patent-Column 1,, line 17 of the Abstract of Disclosure}Specification page 1, line 16 of the Abstract of Disclosure 5' shouldread 5 Printed Patent Column 5, Claim 1; (Formula) I I on} 1 m PrintedPatent reads: H

02 I fil-OO-t-butyl CH3 I 2 L L w Signed and sealed this 23rd day ofApril 1971 (S-ML) Attest;

v ammo a c. MARSHALL DANN Attesting Officer- Commissioner of Patents

